Tumour budding in invasive ductal breast carcinomas: correlation with clinicopathological prognostic parameters and hormone receptor status.

Introduction: Breast cancer is a leading cause of morbidity and mortality among women. Advances in molecular biology have improved detection and treatment, but conventional histopathological factors remain crucial for prognosis. Tumour budding, defined as clusters of less than 5 tumour cells detached from the main tumour, has been linked to poor prognosis in several cancers. This study explores the association between intra-tumoral budding (ITB) and peripheral tumour budding (PTB) with known prognostic factors in Invasive Breast Carcinoma of no special type (IBC NST). Materials and methods: This retrospective study analysed 70 cases of IBC NST diagnosed at Kasturba Medical College, Manipal, between January 2020 and December 2021. Tumour budding was classified as high-grade or low-grade based on density, which denotes the number of buds per x20 field. Clinicopathological data, including hormone receptor status, Ki-67 index, lymphovascular invasion (LVI), perineural invasion (PNI), and axillary lymph node involvement, were obtained. Statistical analyses were performed to identify a significant association between tumour budding and these factors. Univariate and multivariate logistic regression analyses were also done to demonstrate the significance of association. Results: High-grade PTB showed significant associations with LVI (p = 0.046), PNI (p = 0.017), and axillary lymph node involvement (p = 0.021). In contrast, high-grade ITB was only significantly correlated with axillary lymph node involvement (p = 0.044). LVI (p-value = 0.240) and axillary lymph node involvement (p-value = 0.142) did not show any association with PTB on multivariate analysis and PNI (p-value = 0.074) near significant association with PTB). A significant inverse association was observed between PTB and Ki-67 (p = 0.012), which remained significant in univariate and multivariate analysis (p-value = 0.017). No significant associations were found between tumour budding and hormone receptor status or menopausal status. Conclusion: Peripheral tumour budding (PTB) is significantly associated with several poor prognostic factors in IBC NST, while intra-tumoral budding (ITB) correlates primarily with axillary lymph node involvement. Tumor budding, particularly PTB, could serve as an important prognostic marker in breast cancer. Further research is needed to standardize tumour budding assessment in clinical practice.